Automatic readjusting and feeding device for a hydraulically operated scraping device in a peeling centrifuge



K. KOSLOWSKI ETAL AUTOMATIC READJUSTING Aug, 29, 1967 3,338,418

AND FEEDING DEVICE FOR A HYDRAULICALLY OPERATED SCRAPING DEVICE IN A FEELING CENTRIFUGE Filed Feb. 11, 1964 2 Sheets-Sheet 1 FIG. 7

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AUTOMATIC READJUSTING AND FEEDING DEVICE FOR A HYDRAULICALLY OPERATED SCRAPING DEVICE IN A FEELING CENTRIFUGE Filed Feb. 11, 1964 2 Sheets-Sheet 2 28 m /I A/// INVEN ORS United States Patent 3,338,418 AUTOMATIC READJUSTING AND FEEDING DE- VICE FOR A HYDRAULICALLY OPERATED ggllgllNG DEVICE IN A FEELING CENTRI- Karl Koslowski, Dortmund-Solde, and Fritz Walter Schneider, Schwerte (Ruhr), Germany, assignors to Beteiligungsund Patentverwaltuugsgesellschaft mit beschrankter Haftung, Essen, Germany, a corporation of Germany Filed Feb. 11, 1964, Ser. No. 343,970 Claims priority, application Germany, Feb. 23, 1963, K 49,041 4 Claims. (Cl. 210--375) The present invention relates to an automatic readjusting and setting device for a hydraulically operated scraping device with a reciprocating as well as a rotating knife shaft in a peeling centrifuge.

For the scraping of dry centrifuged solid materials out from the centrifuge drum of a peeling centrifuge conventionally blade-like peeling knives are used, which, by means of arms, are arranged on a shaft extending parallel to the drum axis. The peeling knife is moved along the cake of solid material and swings into the latter, respectively, by means of an axial reciprocation and 'an intermediately performed rotation of this shaft for a small amount. By means of a imultaneous rotation of the centrifuge drum, the cake of solid material is thereby peeled at a depth corresponding to the rotation of the knife shaft. This procedure is comparable with the cutting of a bore on the lathe. The peeled solid material is caught in a receptacle or removed from the centrifuge drum by means of a chute or a conveyor screw. The reciprocating movement of the peeling knife in axial direction and the displacement in the respective end positions of the knife shaft is repeated as long until the cake of solid material is scraped out from the centrifuge drum. Thereafter, the peeling knife is returned into its starting position.

In a known hydraulically operated scraping device the reciprocating movement of the knife shaft is brought about by a piston reciprocating in a hydraulic cylinder, which piston is subjected simultaneously to pressure on its opposite faces and which cylinder is arranged outside the centrifuge housing. The rotation of the knife shaft causing the setting of the knife is performed either by a piston of a setting cylinder, which piston is laterally pivoted to the knife shaft, or by a rotary piston coupled with the latter.

In the known devices of the type mentioned above, the automatic readjusting for the reciprocating movement of the knife shaft is performed by a pre-control slide mechanically operated by the knife shaft. A pressure oil connection to the working space of the setting cylinder is, thereby, created for a short time period in the end positions of this pre-control slide and thus the setting movement is obtained. The length of this setting movement of the peeling knife and thus the depth of cutting can, thereby, be adjusted to a certain extent either by adjustable abutments upon the operating members for the pre-control slide or by throttle installations in the pressure oil conduit to the setting cylinder.

These known control devices are though relatively simple in their structure and suitable without fail for normal conditions. It has been found, however, that, if these devices are used, the depth of cutting cannot be set sufi'iciently exact and maintained in the set position, in particular, if extremely varying scraping forces are encountered, since the size of the setting movement is dependent upon the pressure and the viscosity of the hydraulic oil and is thus also variable with the oil temperature. Due to this arrangement, the scraping times per charge do not remain constant. Within the aim for complete automation til of the centrifuging procedures in peeling centrifuges, it is desirable, however, to maintain constant as much as possible the scraping times per charge, in order to bring about thereby an always equal output as to the quantity, equal results and an increase in the efliciency.

Furthermore, the danger exists in the known devices of this type, that upon break-down of the setting in the end positions of the knife shaft, the pressure oil connection to the working space of the setting cylinder, brought about by the pre-control slide, remains open for a longer time period, so that the peeling knife is moved in one stroke into the rotating centrifuge drum. Forces can, thereby, occur, which lead to the destruction of the drum shaft.

It is, therefore, one object of the present invention to provide an automatic adjusting and feeding device for a hydraulically operated scraping device in a peeling centrifuge, wherein the described drawbacks are avoided.

It is another object of the present invention to provide an automatic adjusting and feeding device for a hydraulically operated scraping device in a peeling centrifuge, wherein an automatic readjusting and feeding device is created by which a constant setting movement is obtained even in case of varying oil viscosities and load conditions. Furthermore, the length of this setting movement and thus the depth of cutting should be settable in a possibly simplest manner.

It is still another object of the present invention to provide an automatic adjusting and feeding device for a hydraulically operated scraping device in a peeling centrifuge, which includes a particular dosing slide which is subjected to pressure on both sides and whose cylinder can be connected at its ends alternately with the supply conduit for the pressure oil and with the working space of the setting cylinder, whereby the readjustment is performed always in the end positions of the reciprocating knife shaft by means of a precontrol slide mechanically operated by the knife shaft.

Due to the interposition of a dosing slide in the pressure oil conduit to the setting cylinder, a length of the setting movement is assured by simple means, which is independent from the varying oil viscosities and load conditions. Moreover, this length and thus the depth of cutting can be adjusted in a simple manner by a corresponding variation of the stroke volume.

It is also an object of the present invention to provide an automatic adjusting and feeding device for a hydraulically operated scraping device in a peeling centrifuge, wherein the readjusting slide for the reciprocating movement of the knife shaft is designed such, that it surrounds annularly the dosing slide in its center portion and is operated by the latter. Due to this design, it is possible to guide the readjusting slide in the center portion of the cylinder for the dosing slide, which cylinder, therefore, includes also in this portion the oil bores for the readjusting of the knife shaft.

Suitably, the dosing slide, which anyway does not require substantially more space compared with the known devices, is combined in one single control block jointly with the remaining control members.

The readjusting and feeding device according to the present invention makes possible a greater accuracy and safety of the scraping procedure in relation to the known structures in spite of the substantially equal space resetting device;

FIG. 2 is a section along the lines 22 of FIG. 1; and

FIGS. 3, 4 and 5 are schematic cross-sections of the readjusting and setting device at an enlarged scale, disclosing three different positions thereof.

Referring now to the drawing, the scraping device comprises a centrifuge drum 1 which runs during the scraping in a centrifuge housing 2 at a constant number of revolutions, which is reduced relative to the number of revolutions during the filling operation. The scraping device with its control device is mounted in a housing cover 3. Peeling knives 4 are secured laterally on a knife shaft 6 by means of arms 5 within the centrifuge drum 1. One end of the knife shaft 6, projecting from an opening in the housing cover 3 is a piston 7 which reciprocates in a hydraulic cylinder 8. The cylinder 8 is rotatably mounted in roller bearings 9 within a housing 10 disposed adjacent to the housing cover 3. The rotary movement of the cylinder 8, during which the latter takes along the knife shaft 6 by means of a slide key 11, is brought about by means of a piston 13 reciprocating in a hydraulic setting cylinder 14, which piston 13 is pivotally connected to arms 12 which project radially outwardly from the cylinder 8. The hydraulic setting cylinder 14 is swingably mounted in the housing 10 by means of pins 15 (FIG. 1). A screw bolt 16, adjustably disposed in the housing 10 (FIG. 2), serves as an abutment for the extent of the swinging movement of the cylinder 8 and, thereby, simultaneously for the setting movement of the peeling knives 4 in the centrifuge drum 1.

A control block 17, disposed next to the housing 10, which contains the actual shifting and setting device, is operatively connected by one of its movable parts with the piston 7 over a double-armed control lever 18.

Furthermore, the control block 17 is connected with an oil tank 21 of a program control by means of two hydraulic conduits 19 and 20 and by means of two further hydraulic conduits 22, 23, with both ends of the hydraulic cylinder 8. Finally, two further hydraulic conduits 36 and 20 lead to both ends of the setting cylinder 14. The conduits 22, 23, 36 and 20' are flexible, in order to permit the rotary movement of the cylinder 8 and the swinging movement of the cylinder 14, respectively. A pro-control slide 24 is provided in the control block 17, which slide has three annular recesses and reciprocates in a complementary chamber 24'. A- dosing slide is also arranged in the control block 17, which dosing slide comprises two pistons 31 and 32 with a connecting rod 32 and reciprocates in the end chambers 33 and 34, respectively.

The structure and the mode of operation of the device designed in accordance with the present invention will be apparent from FIGS. 3-5 of the drawings.

In the starting position, shown in FIG. 3, for the setting and longitudinal movements, the piston 7 and, thereby, also the knife shaft 6 with the knives 4, is disposed in the left end position. From the program control 21, pressurized oil is fed now into the conduit 19, while the conduit 20 serves as a return conduit. As can be ascertained from FIG. 3, the pressurized oil is fed from the conduit 19 directly into the conduit 22 and simultaneously, by means of an annular recess 38', provided in a second precontrol slide 38, into the conduit 23. The piston 7 is, thus, simultaneously subjected on both sides to the pressurized oil. Since, however, the left face of the piston 7, subjected to pressure through the conduit 23, is larger, the piston 7 and, thus, the knife shaft 6 move to the right. A piston rod 28 is moved thereby, which piston rod 28 extends with a piston 28 into a cylindrical chamber 28" of the piston 7 and carries a collar 28", by means of engagement with the collar 27 of the piston 7, the piston rod 28 has been moved to the left previously. Since the piston rod 28 is operatively connected with the precontrol slide 24 by means of the two-armed lever 18, the latter is moved also and adjusts itself due to the pressure of two helical springs 25 and 26 in its middle position. The helical springs 25 and 26 engage the two ends of 4 the pre-control slide 24 by means of two movable plates 25' and 26'. Due to this movement, the position disclosed in FIG. 4 has been obtained.

Shortly before the piston 7 arrives at its right end position, it joins the piston 28' by means of the collar 27 of the piston 7 and, thus, moves the piston rod 28 further to the right. The pre-control slide 24 is thereby moved by means of the double-armed lever 18 from its middle position into the left end position, shown in FIG. 5. As can be ascertained from FIG. 5, a connection of the pressurized oil conduit 19 with the conduit 30 by means of the conduit 29 is established, which conduit 30 terminates in the chamber 33. Due to the pressure exerted now upon the piston 31, the dosing slide is moved into is right end position, shown in FIG. 5, and the oil displaced from the chamber 34 by the piston 32, which displaced oil quantity corresponds with the stroke volume of the dosing slide, is fed into the working chamber 37 of the setting cylinder 14 by means of the conduits 35 and 36. By lowering the piston 13 in the setting cylinder 14 and by the rotary movement of the cylinder 8 caused thereby and of the knife shaft 6, the desired setting movement of the peeling knives 4 is obtained in the centrifuge drum 1.

The control slide 38, which surrounds the connecting rod 32 annularly in the center portion of the dosing slide and is shown in FIGS. 3 and 4 likewise in its left end position, is joined in the movement shortly before termination of the movement of the dosing slide to the right from the back face of the piston 31 and brought into the right position, shown in FIG. 5. Due to the displacement towards the right of the annular recess 38', the hydraulic conduit 23 is no more connected with the pressure conduit 19, rather with the return conduit 20. The piston 7 is, thus, subjected to pressure only through the conduit 22 and moves, thus, to the left, whereby the control slide 24 is returned again at first into its middle position (FIG. 4) and only shortly before reaching the left end position of the piston 7 arrives in its right end position (FIG. 3). The conduit 29, which is connected continuously with the pressure conduit 19 is, thus, connected with the chamber 34 by means of the conduit 35, whereby the dosing slide is moved again to the left due to the oil pressure effective on the piston 32. The oil displaced by the piston 31 from the chamber 33 is fed into the working chamber 37 of the setting cylinder 14 through the conduits 30 and 36 and produces thereby a further setting movement of the peeling knives 4. The dosing slide joins again, this time with the back face of its piston 32, the control slide 38 during its movement to the left, shortly before reaching its left end position. By this movement, the position disclosed in FIG. 3 is restored again.

The reciprocating movements of the piston 7 in the cylinder 8 and the stepwise, downwardly directed movements of the piston 13 in the setting cylinder 14 in both end positions of the piston 7 are repeated for such time until upon reaching the desired degree of scraping a further downwardly directed movement of the piston 13 is prevented by engagement of the arm 12 of the cylinder 8 with the screw bolt 16. From now on the oil, displaced by the pistons 31 and 32 of the dosing slide, flows through the relief valve 40 disposed in the conduit 39 directly into the return conduit 20. After a few further reciprocations of the knife shaft 6, which serve the smoothening of the layer of solid material remaining in the centrifuge drum 1, the program control system 21 switches the scraping device, by shifting the flow of pressure oil from the pressure conduit 19 to the return conduit 20.

The piston 13 is returned into its starting position by means of the oil pressure acting through the former return conduit 20 onto the rear face of the piston 13, whereby the oil, displaced from the operative chamber 37, flows off through the conduit 41 and the non-return valve 42 into the present return conduit 19. Thus, the scraping device is available for the next scraping cycle.

-In order to provide adjustment of the volume of the dosing slide, the connecting rod 32 between its pistons 31 and 32 projects laterally from the control block 17 and is formed as a threaded spindle, which is rigidly connected with the piston 32, while the piston 31, secured by a key 31' against rotation, is screwed onto the thread of the spindle. By rotation of the spindle by means of a manually operable gripping device 43 the distance between the pistons 31 and 32 and thus the stroke volume of the dosing slide can be varied according to the particularly desired cutting depth.

While we have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

We claim:

1. An automatic readjusting and setting device for a hydraulically operated scraping apparatus, comprising a housing,

a centrifuge drum rotatably mounted in said housing;

a hydraulically operated scraper device, including a shaft having at least one peeling knife extending radially therefrom,

said shaft being mounted for rotation and reciprocation in said centrifuge drum,

said shaft including a piston,

a first setting cylinder controlling the rotary movement of said shaft and having an operating chamber,

a first pre-control slide controlling the reciprocation of said shaft,

a hydraulic actuator including said piston,

pressure and outlet connections between said first precontrol slide and said hydraulic actuator,

said first precontrol slide being periodically shifted to control said pressure and outlet connections to said hydraulic actuator, in order to reciprocate said shaft,

a second cylinder having a chamber ateach end therea double-acting dosing piston reciprocating in said second cylinder,

a pressure supply line,

means for connecting said end chambers of said second cylinder alternately to said pressure supply line and to 7 said operating chamber of said setting cylinder,

a second pre-control slide including return springs,

means for actuating mechanically said second precontrol slide upon reaching the end positions of the reciprocating movement of the first mentioned piston to reverse the pressure connections to said end chambers of said second cylinder, and, thereby to shift said dosing piston, and

the shifting movement of said closing piston being effective to displace liquid under pressure from said end chamber into said setting cylinder to effect stepwise rotation of said shaft and effecting the periodic shifting of said first pre-controlled slide.

2. The device, as set forth in claim 1, which includes means for adjusting the stroke of said dosing piston.

3. The device, as set forth in claim 1, wherein said first pre-control slide surrounds annularly the center portion of said dosing piston.

4. The device as set forth in claim 1, wherein said dosing piston, said first and second pre-control slides, and said pressure supply line are disposed in said hydraulically operated scraper device as a unit.

References Cited UNITED STATES PATENTS 1,965,840 7/1934 Jones 210376 X FOREIGN PATENTS 821,47 8 11/ 1951 Germany. 779,183 7/1957 Great Brtiain.

OTHER REFERENCES German printed application 1,091,040, October 1960.

REUBEN FRIEDMAN, Primary Examiner. I. DECESARE, Assistant Examiner. 

1. AN AUTOMATIC READJUSTING AND SETTING DEVICE FOR A HYDRAULICALLY OPERATED SCRAPING APPARATUS, COMPRISING A HOUSING, A CENTRIFUGE DRUM ROTATABLY MOUNTED IN SAID HOUSING; A HYDRAULICALLY OPERATED SCRAPER DEVICE, INCLUDING A SHAFT HAVING AT LEAST ONE PEELING KNIFE EXTENDING RADIALLY THEREFROM, SAID SHAFT BEING MOUNTED FOR ROTATION AND RECIPROCATION IN SAID CENTRIFUGE DRUM, SAID SHAFT INCLUDING A PISTON, A FIRST SETTING CYLINDER CONTROLLING THE ROTARY MOVEMENT OF SAID SHAFT AND HAVING AN OPERATING CHAMBER, A FIRST PRE-CONTROL SLIDE CONTROLLING THE RECIPROCATION OF SAID SHAFT, A HYDRAULIC ACTUATOR INCLUDING SAID PISTON, PRESSURE AND OUTLET CONNECTIONS BETWEEN SAID FIRST PRECONTROL SLIDE AND SAID HYDRAULIC ACTUATOR, SAID FRIST PRECONTROL SLIDE BEING PERIODICALLY SHIFTED TO CONTROL SAID PRESSURE AND OUTLET CONNECTIONS TO SAID HYDRAULIC ACTUATOR, IN ORDER TO RECIPROCATE SAID SHAFT, A SECOND CYLINDER HAVING A CHAMBER AT EACH END THEREOF, A DOUBLE-ACTING DOSING PISTON RECIPROCATING IN SAID SECOND CYLINDER, A PRESSURE SUPPLY LINE, MEANS FOR CONNECTING SAID END CHAMBERS OF SAID SECOND CYLINDER ALTERNATELY TO SAID PRESSURE SUPPLY LINE AND TO SAID OPERATING CHAMBER OF SAID SETTING CYLINDER, A SECOND PRE-CONTROL SLIDE INCLUDING RETURN SPRINGS, MEANS FOR ACTUATING MECHANICALLY SAID SECOND PRECONTROL SLIDE UPON REACHING THE END POSITIONS OF PISTON TO REVERSE MOVEMENT OF THE FIRST MENTIONED PISTON TO REVERSE THE PRESSURE CONNECTIONS TO SAID END CHAMBERS OF SAID SECOND CYLINDER, AND THEREBY TO SHIFT SAID DOSING PISTON, AND THE SHIFTING MOVEMENT OF SAID CLOSING PISTON BEING EFFECTIVE TO DISPLACE LIQUID UNDER PRESSURE FROM SAID END CHAMBER INTO SAID SETTING CYLINDER TO EFFECT STEPWISE ROTATION OF SAID SHAFT AND EFFECTING THE PERIODIC SHIFTING OF SAID FIRST PRE-CONTROL SLIDE. 